The golf course bunker originated in Scotland and Ireland as a hazard on the golf course (other hazards including rough areas, water, mounds, trees and the like), where these hazards are included in a golf course design as obstacles for strategy and direction, as well as for aesthetic purposes. In its earliest form, the bunker was more of a natural sand pit and was not formally maintained. In time, design styles changed and the bunker became a formalized tool that was utilized by course designers to create unique challenges for golfers. Indeed, most of the great, well-known golf courses include dramatic bunkers, where their styles vary from steep slopes with sand or turf to expansive areas with relatively flat contours.
Contemporary bunker maintenance is a major part of a golf course superintendent's responsibilities. Indeed, the time required to maintain bunkers at their expected high degree of quality can be challenging, particularly on courses that include upwards of a hundred bunkers or more. While maintenance crews spend a certain amount of time repairing bunker damage resulting from golf play, the majority of bunker maintenance is associated with repair from rain events and other environmental causes. Indeed, when a rainstorm occurs, the required repair work on bunkers may be extreme. For example, when a storm event occurs, the sand can be washed from the high spots on bunker slopes to lower regions in the bunker, exposing the subsoil on the slopes. The sand can be contaminated by subsoil color or even become mixed with stone particles that form the lower drainage area of a bunker. Inasmuch as this contamination is almost impossible to remove from the sand, the old sand is usually removed and replaced with fresh sand, increasing bunker maintenance costs.
There have been some attempts in the past to address these problems associated with golf course bunker maintenance. In some cases, fabric liners have been installed as a barrier between the subsoil and the bunker sand. However, these liners tend to degrade over time, and are known to have a limited holding capacity, particularly on slopes. Liners are also held in place by metal stakes that may become exposed (especially in northern climates) due to ground freeze/heaving, etc.
Instead of a liner formed as a sheet of material, other solutions have used spray coatings of a material over the subsoil. In some cases, a concrete spray is used. Again, this material tends to degrade over time and is especially sensitive to the temperature variations associated with northern climates (particularly ground freeze). These coatings are also difficult to repair and minimize the ability of the course to modify the bunker design without totally demolishing the concrete material.
Various types of aggregate materials have also been used as a thin boundary layer between the subsoil and the sand, creating an area with improved drainage and defining a physical boundary between the sand and the subsoil. Aggregates such as a bituminous layer with stone aggregate, polymer spray stone aggregate and rubber-polymer layers with stone aggregate have all been used. Regardless of the material selection, these aggregate structures have been found to have limited holding capacity against steep bunker slopes and tend to move downward over time, thus causing the covering sand to move as well. Again, these aggregate arrangements are difficult to repair and require a total bunker reconstruction if a design change is desired.
Thus, a need remains in the art for an arrangement that provides the drainage characteristics necessary to maintain the longevity and appearance of a golf course bunker, while providing the necessary protection of steep slopes and allowing for bunker design modifications to be accommodated.